1. Field of the Invention
The present invention relates generally to devices for determining the physical properties of materials, and particularly to an apparatus for determining coefficients of friction of various materials as they travel along a surface. The surface material may be interchanged for testing the various materials as they travel over different surfaces.
2. Description of the Related Art
The precise determination of the physical properties of various materials is useful in many fields in addition to the purely theoretical or academic world. An example of such is found in the determination of the static and dynamic (sliding) coefficients of friction between paved surfaces and vehicle tires traveling over those surfaces. Different surfaces, e.g., asphalt or concrete, exhibit different static and dynamic coefficients of friction between those surfaces and a given rubber tire bearing upon the surfaces. Moreover, in the past it was believed that tires having a tread pattern (grooves, etc.) provided greater static or rolling adhesion to the underlying surface than did “slick” tires, i.e., tires having an unbroken rubber surface devoid of grooves and/or other discontinuities. This has been shown to be erroneous. Tires having a smooth, unbroken surface are recognized as providing a higher static coefficient of friction, i.e., greater adhesion, than tires having a tread pattern, at least on dry surfaces. The only means of precisely establishing these factors is through precise tests.
The precise determination of dynamic or sliding coefficients of friction between different materials is also useful in the reduction of internal resistance in various mechanical devices, such as internal combustion engines, transmissions, and differentials. This particular field has assumed great importance, as even very small improvements in efficiency result in significant reductions in wasted energy and significant improvements in fuel economy when a large fleet of vehicles (automobiles, aircraft, ships, etc.) is considered.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, an apparatus for determining coefficients of friction solving the aforementioned problems is desired.